The Tissue Bank Core C will provide the necessary mechanism to collect and distribute tissues from large[unreadable] numbers of patients to individual investigators. Because Ph negative MPD are relatively rare, individua[unreadable] investigators at a single institution cannot obtain tissues from sufficiently large numbers of patients to reach[unreadable] statistically valid conclusions within a reasonable time frame without Tissue Core C. Tissue Core C will[unreadable] provide tissues from large cohorts of patients at various stages of these disorders, as well as tissues from[unreadable] individual patients collected longitudinally during disease progression. Thus, the Tissue Bank Core C will be[unreadable] an invaluable tool to current and future studies on MPD.[unreadable] The specific aims of the Tissue Bank Core C are to:[unreadable] 1) Receive, process, and store tissues from MPD patients diagnosed at MPD Consortium clinical sites[unreadable] in an efficient and organized way. 2) Provide a central repository for MPD tissues that can be associated[unreadable] with basic data to be stored by Biostatistics and Data Management Core B. These data will include clinical[unreadable] laboratory data and familial demographics that will enable selection and distribution of tissues best suited for[unreadable] each translational research project. 3) Make the viably frozen tissues readily available to the MPD[unreadable] Consortium investigators for research studies. When available, tissues will also be available to the scientific[unreadable] community at large. 4) Perform biomarker assays, designed to predict disease progression and thrombotic[unreadable] complications, on MPD samples received at the time of diagnosis, and periodically during therapy.[unreadable] The functions of Tissue Bank Core C will be to: 1) acquire Ph negative MPD tissues, 2) act as a repository[unreadable] for the Ph negative MPD tissues, 3) distribute the MPD tissues research, and 4) perform biomarker analyses.[unreadable] Tissues collected will be available to members of the MPD Consortium and to the scientific community at[unreadable] large. Tissue Bank Core C will significantly facilitate translational research that will enhance diagnosis and[unreadable] staging of MPD and ultimately lead to the development of molecularly targeted therapies.[unreadable] PV and IM are disorders for which there are currently no effective treatments. PV and IM affect primarily[unreadable] patients > 50 years of age and their annual incidences are estimated to be 2.8 and 0.4/100,000 people,[unreadable] respectively. The number of people over the age of 50 is increasing and therefore more people will be[unreadable] affected by these disorders in the future. Therefore, from a public health perspective it is imperative to[unreadable] develop effective therapies.